One big difference between shopping in the UK and Hong Kong is the degree of consumer protection that exists.
For example, in the UK shops cannot advertise a price reduction unless the goods were sold at the higher price for a certain period, and they must state the price per kilogramme or litre for food items. Not in Hong Kong.
Hence, Park'n'Shop don't have to draw attention to the fact that a 1 litre bottle of their own-brand olive oil costs HK$70 per litre, whilst a 500 ml bottle costs HK$60 per litre. Yes, most customers are able to figure it out (at least if they are spending their own money) but why should we have to do so. I suppose that the only explanation for this bizarre pricing policy is that PnS are using these prices merely to establish a benchmark from which they can advertise reductions - one week it was 'buy one, get one free' on 250 ml (effective price HK$42 per litre), then it was 'three for HK$60' on the 500 ml bottle (HK$40 per litre).
Another random example is that Giordano sell belts officially priced at HK$100 each. However, they actually seem to sell them either at HK$60 ("40% off") or HK$50 ('buy one, get one free'). If they ever sell them for the stated price of HK$100 it is probably only for a day or two after one special event ends and before the next one starts. This would be illegal in the UK, where the government does its very best to protect people from sharp practice on the part of retailers, apparently figuring that they are unable to do this for themselves.
Well, I can probably separate a genuine bargain from a imaginary one, but comparing the price of products with both metric and imperial measures in a variety of different sizes does sometimes tax my brain. However, I'm not holding my breath waiting for this type of labelling to appear in my local Park'n'Shop.